The invention relates to a method for producing a container having an inside bag for the accommodation of a filling material which is applied by a propellant between the container and the inside bag from a valve or the like. After production of the container, for example by pressing, deep drawing or the like, its interior is provided with an inside protective lacquer and subsequently primed. Plastic for the inside bag is injected upon the primer and subsequently the container having the inside bag is subjected to heat to remove superfluous solvent from the plastic. A bottom hole is then shaped out in the container for the later introduction of the propellant.
A dual-chamber container of this type is known, for example, from German Offenlegungsschrfit No. 2,360,319.
In that case, the material for the inside bag is applied as a coating, for example by applying the liquid coating material into the pressure vessel through a nozzle. Afterwards the Pressure vessel is turned over so that the superfluous liquid can flow out. Another possibility of coating is introduction by means of a spray head lowered into the interior of the container, the spray head or the pressure vessel itself being rotated in order to guarantee even coating.
However, these methods have proved to be disadvantageous in that the coating or the inside bag is deformed again during the subsequent heating to evaporate the superfluous solvent, due to the fact that the material of the inside bag flows together and air or solvent inclusions are formed which lead to undesired irregularities in the inside bag. Due to these inclusions, the inside bag can even become leaky.
Furthermore, for reasons of cost and production, PVC (polyvinyl chloride) is used in practice for the production of the inside bag. However, a plasticizer must be added to this PVC material so that the inside bag can be folded properly. The plasticizer, in turn, has the disadvantage that it merges into the filling material and the corresponding container is therefore not suitable for foodstuffs, pharmaceuticals or the like. Additionally, when recycling PVC, hydrochloric acid arises which, in turn, considerably impairs the environment.